Early malnutrition may impair infants’ mix of gut microbes

Babies’ microbiomes fail to fully recover even after nutrition improves

Malnutrition in a baby might do more than thwart the child’s growth. A study shows that acutely malnourished babies have an understaffed reservoir of helpful bacteria in their intestines, a problem that lingers even after they are given foods specially designed to help them gain some weight.

The findings suggest that malnutrition damages the array of beneficial gut microbes, or microbiota, that reside in people’s bodies. These microbes appear indispensible to metabolism, immunity, digestion and overall development (SN: 6/18/11, p. 26). An individual’s mix of gut microbes can last decades and function much like an internal organ, says study coauthor Jeffrey Gordon, a physician and microbiologist at Washington University in St. Louis.

Scientists know little about the effects of malnutrition on the gut microbial community early in life, he says. Gordon and his colleagues assessed dozens of babies in Bangladesh, ages 6 to 20 months, who were hospitalized with severe malnourishment in Dhaka. When the researchers tested fecal samples from some of these babies, they found rampant shortages among two dozen beneficial kinds of intestinal bacteria that had been identified in a separate test of healthy babies in Bangladesh.

The malnourished infants were nursed back to health over several weeks with intravenous fluids and antibiotics to clear infections. They also received a gruel containing milk, rice, sugar and soybean oil, followed several days later by either an imported peanut paste or a mixture of lentils and rice that is a common source of protein in Bangladesh. Once the babies’ health had stabilized, they went home.

During monthly checkups, hospital workers found that the infants’ heights and weights remained well below Bangladesh’s national average. The infants’ gut microbiota seemed to rally briefly, but by four months out, the microbes had failed to reach normal levels, the scientists report June 4 in Nature.

Research on healthy babies has shown that microbiota normally expand in number and diversify at a steady pace from infancy to toddlerhood. But in this study babies seemed to fall offtrack after a bout with severe malnourishment. Microbiota levels also lagged in a separate group of moderately malnourished children who underwent similar treatment.

Stanford University researchers Elizabeth Costello and David Relman say fecal test results could be used to develop “an early warning system” for out-of-whack microbiota in malnourished kids. Also in Nature, the researchers describe the human gut as an ecosystem. “Degraded ecosystems are notoriously difficult to restore,” they write. In the case of malnourished babies, they say, “early intervention may be critical.”

Meanwhile, more work is needed, Relman tells Science News. “We all agree this is a valuable thing to be doing.” But he says the genetics and environment of children in other parts of the world would be different than in these Bangladeshi kids, meaning the ideal bacteria used as windows on microbiota status might be somewhat different elsewhere.